Zevachim Daf 78 זבחים דַף 78

The next Mishnah states that if blood of a korban became mixed with water, אם יש בו מראית דם – if it has the appearance of blood, it is valid. If it became mixed with (red) wine, רואין אותו כאילו הוא מים – we view it as if it were water, and if the blood in this amount of water would appear as blood, it is valid. The Tanna Kamma says the same applies if it became mixed with blood of chullin animals, but Rebbe Yehudah says: אין דם מבטל דם – blood does not nullify blood. He holds that מין במינו – a kind mixed with its same kind is never בטל, so the korban’s blood remains valid. Rebbe Yochanan said the Mishnah’s first ruling, permitting זריקה of blood mixed with water, only applies where water fell into the blood, אבל נפל דם לתוך מים – but if blood fell into water, ראשון ראשון בטל – each first drop of blood is nullified as it falls into the water, and cannot be used. Even if the mixture eventually turns red, it may not be used, because of דיחוי – rejection.

Reish Lakish says: הפיגול והנותר והטמא שבללן זה בזה – if someone mixed piggul, nossar, and tamei [kodashim] with one another and ate them, he is completely פטור, although there was a כזית of each איסור, because אי אפשר שלא ירבה מין על חבירו ויבטלנו – it is impossible that one type of איסור should not overwhelm the other and nullify it. Rashi explains that as he chews, parts of each איסור become mixed into the other and בטל to it. Since they will not exchange parts exactly equally, one איסור will invariably emerge larger, and he can only be liable for that איסור. Since this איסור is unknown, the התראה – warning to him is התראה ספק – an uncertain warning. This proves three principles: (1) איסורין מבטלין זה את זה – prohibited items can nullify one another. (2) נותן טעם ברוב לאו דאורייתא – The prohibition to eat food where a forbidden item gives flavor into a majority permitted one is not Biblical. This assumes that the איסורים are different types (e.g., meat and flour), yet he is still not liable for the minority איסור which imparts flavor. However, this principle is disproven, so the case must be מין במינו, where the minority does not give flavor to the majority. (3) התראה ספק is not a valid התראה.

The Gemara asks that even in a mixture of איסורין of מין במינו, the minority should not be בטל; rather, we should calculate it as if it were מין בשאינו מינו – one kind with something not its kind, and if it would give flavor to the majority, it should not be nullified. This is demonstrated from our Mishnah, which taught that if korban blood mixed with wine, "רואין" – we view the wine as if it is water and the blood remains valid for זריקה. Furthermore, in a Baraisa, where a [tamei] bucket which had white wine or milk in it, which was immersed in a mikveh, Rebbe Yehudah says: רואין אותו כאילו הוא יין אדום – we view [the wine or milk] as if it were red wine: אם דיהה מראהו כשר – if there is so little wine that its color would have become faint through dilution of the mikveh water, the tevilah is valid. But if the redness of the wine would still be present, the tevilah is not valid (although this wine is actually white)!? The Gemara concludes that the question of "רואין" is a machlokes Tannaim, because the Tanna Kamma argues with Rebbe Yehudah and says: הולכין אחר הרוב – we follow the majority, and if most of the liquid is water, the tevilah is valid.